Some perspective you might need here:

1- It's not feasible to screen all the virus present in a bat population. If you tried you'd likely find many new virus no one ever described and still only know a small subset of the viral population within the bat population.

2- Vírus won't stay still and remain the same. The sars-cov-2 we have today is different from the one we first described and that would also apply to it's ancestors. Even if we find this ancestor it wouldn't be a 100% match. Parasites adapt to their hosts and sars-cov-2 jumped the species barrier at least once and maybe twice. The simple fact that a virus is in different hosts put new selective pressures on them.

3- We have find similar virus in the wild. The RaTG13 has around 96% identity to sars-cov-2 genome. This is not enough to say that one came from the other but shows that we can find some similar things if we look closely to betacoronavirus populations in bats.